Improvement in separation performance of Matrimid®5218 with encapsulated [Emim][Tf2N] in a heterogeneous structure: CO2/CH4 separation

The superior features of Matrimid®5218 polymer and 1-ethyl-3-methyl imidazolium bis(trifluoromethylsulfonyl) imide ([Emim][Tf2N]) as an ionic liquid (IL) were combined to prepare efficient membranes for CO2/CH4 separation. The blended membranes, which were prepared with direct physical mixing of the polymer and the IL, were characterized by structural analyses such as SEM, DSC, FTIR-ATR, and tensile tests. During the membrane preparation procedure, heterogeneous structures with fixed and well-distributed IL ponds were created. Transport properties i.e. permeability, diffusivity, and solubility of the blended membranes with different IL contents (10, 20, 30, and 40 wt% based on the polymer weight) were evaluated at different operating conditions. With encapsulating IL into the ponds within the polymeric matrix, the membranes were able to operate appropriately for gas separation. For instance, at the transmembrane pressure of 8 bar and 35 °C for the membrane with 40 wt% [Emim][Tf2N], the CO2 permeability coefficient was increased from 6.5 to 38 Barrer, about 484%, and the CO2/CH4 permselectivity value was increased from 32 to 63, about 96%. The prepared polymer/IL blended membranes are realized to be superior candidates for CO2/CH4 separation.